Aviator has Misfire. | Ford Explorer Forums - Serious Explorations

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Aviator has Misfire.

dgr6853

Active Member
Joined
January 14, 2010
Messages
61
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City, State
Stockton, Ca
Year, Model & Trim Level
2003 Lincoln aviator
My Aviator has had an occasional misfire. It started with Cylinder 7 and then spread to cylinder 4. This has been going on now for about a month. I do get an accumulation of oil on the passenger head spark plug wells.--I think I have a bad valve cover gasket. I simply drain them and burn them off and when I did that about a week ago, the misfires went away but they have come back. Right now I have

p0304-cylinder 4 misfire detected
p0316-misfire detected on startup (first 1000 rpms)
p0307-cylinder 7 misfire detected.

Also, every now and then I get a "multiple random misfire detected" though it is not showing right now. in the past that ""multiple random misfire detected" has shown up but I have since reset and cleared the DTC's.

My next step is going to be to start replacing coils one by one. I know the Motorcraft ones are good. However, Autozone doesn't have that and it looks like what they have are a bunch of duralast coils and they have a set of Denso's. Just wondering if anyone has any experience with the Denso coil packs or if there is another coil pack brand I should consider.

Also, looking for any ideas as to where this could be coming from. Considering that I know it could be compression issues like valves not closing or rings needing work or even fuel delivery like faulty injectors.

I think I'm going to start chasing it down with coils first. Also, I wanted to know if this engine with The COP coils have the paired cylinders like cobras that have the two main coil packs at the front of the engine.....it would appear so because if usually cylinder 7 and 4 are paired cylinders. My understanding is that with paired cylinders then if 7 or 4 are misfiring then both are misfiring.

Thanks in advance for your help.

Thank You,
 



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Have you replaced the plugs or just cleaned them? The plug could be bad, and as it heats up stops firing.
 






Have you replaced the plugs or just cleaned them? The plug could be bad, and as it heats up stops firing.
I replaced the plugs about 5000 miles ago. They're new. Relatively. I suppose I could replace them again.
 






Verify that it is oil first. It may be dark and brown but might not be oil. SyberTiger developed a good test for this. Dip a qtip or paper towel into the liquid and then try and ignite it with a flame. If it burns then yes it's oil, but if it doesn't then it's probably coolant leaking into the wells from intake manifold gaskets. I suspect you will find its coolant. Mine looked for all the world to be dark oil in the plug wells but it was coolant mixed with dirt and grime. If your turns out to be coolant then I bet you have failing intake manifold
 






Another thing to try... inspect your boots and the spring wire inside for grunge and build up. I think a couple of the coil over plugs that I replaced were actually ok and the spring inside the boot was trashed from sitting in coolant for so long. You can easily buy just the boots and new springs and swap those on the two cylinders to see if your coil maybe still good. I bought a set of eight DENSO boots from Rock Auto about $20-25
 






Another thing to try... inspect your boots and the spring wire inside for grunge and build up. I think a couple of the coil over plugs that I replaced were actually ok and the spring inside the boot was trashed from sitting in coolant for so long. You can easily buy just the boots and new springs and swap those on the two cylinders to see if your coil maybe still good. I bought a set of eight DENSO boots from Rock Auto about $20-25
I think I'll try that first...as in before I swap out coils. The boots I think are like 4 bucks each at orielys
 






Yes, as long as the new boot also has spring with it. My springs in the wells that sat in liquid the longest had so much gunk and crud I can't believe they ran at all muchless only misfired.
 






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